Pulsed code generation equipment



Sept. 14, 1965 P. PROUTY PULSED CODE GENERATION EQUIPMENT 2 Sheets-Sheet 1 Filed May 28, 1962 L Y H M@ M@ W mm a 1. N

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United States Patent PULSED CODE GENERATION EQUIPMENT Thomas P. Prouty, Costa Mesa, Calif assignor, by mesne assignments, to MHD Research, Inc., a wholly-owned subsidiary of Hercules Powder Company, New Castle County, Del.

Filed May 28, 1962, Ser. No. 198,372 13 Claims. (Cl. 340365) This invention relates generally to the coding of information, and more particularly concerns the production of coded trains of high power pulsed electrical energy, useful in the transmission of pulse coded information using magnetron or klystron type oscillators.

A major object of the invention is to provide for producing, transmitting and selectively coding electrical signals, energy for the production of which is derived from the interaction between a mass traveling at high velocity and a magnetic field. Basically, the apparatus may be considered to comprise a series of electrical signal producing instrumentalities, means for energizing them in series sequence to initiate-signal production in desired time sequence, such means typically including a mass ejector to direct ejected mass along a path passing the instrumentalities in sequence, and circuit means to transmit sequentially and to control sequential transmission of the signals in selected code pattern.

In one of its forms the invention includes a magnetohydrodynamic power generator in which a burst of highly conductive plasma is directed along a channel which is provided with a magnetic field perpendicular to the flow and is also fitted with multiple electrode pairs whose axes are perpendicular to both the axis of plasma flow and the magnetic field. The plasma may be derived from a shock tube, an explosive charge, an electrical discharge, or the like. As the burst of ionized plasma passes the electrodes it interacts with the magnetic field to produce a voltage difference between the electrodes. If a load is connected across the electrodes, current will flow and part of the kinetic energy of the plasma will be converted to electrical energy and dissipated in the load, the plasma experiencing a loss in velocity as a result of this interaction. The electrical output will be' in the form of a pulse having an approximately rectangular shape, and a similar pulse will appear at each electrode pair but the pulse at successive electrode pairs will occur serially in time, with or without overlap, depending, among other things, on electrode width and spacing. By placing a switch in series with each electrode pair, its output may be either connected to its normal load (such as a magnetron) or deverted or left open. By proper manipulation of the switches, pulse coded trains may be generated and delivered to the load. The number of electrode pairs and switches employed will vary in application depending on the character of the required code. One coded pulse train will be generated for each burst of plasma that is generated and caused to flow along the channel.

These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following detailed description of the drawings, in which:

FIG. 1 is a circuit diagram showing one form of the invention;

FIG. 2 is a fragmentary view taken on line 22 of FIG. 1; and

FIGS. 2a, 3, 4 and 5 illustrate other embodiments of the invention.

Referring first to FIGS. 1 and 2 the apparatus will be seen to include a series of signal producing instrumentalities, typically consisting of a series of longitudinally spaced electrode pairs -14, the electrodes of each pair See being laterally spaced apart at opposite sides of a path generally indicated at 15. For reasons which will be later described, the gaps between successive pairs of electrodes decrease in longitudinal dimension in the direction of the path 15. The electrodes themselves may constitute any refractory metal such as tungsten, tantalum and zirconium.

Means is provided for energizing the electrodes in series sequence, thereby to initiate signal production in desired time sequence. Such means typically includes a mass ejector 16 for directing mass along the path 15 passing the instrumentalities 10-14 in sequence. The mass ejector may comprise a source of electrically conductive plasma as for example a shock tube, an explosive charge, an electrical discharge or the like.

The means for energizing the electrodes also includes equipment to produce at the electrodes a magnetic field, and in the embodiment of FIG. 1, such equipment has spaced magnetic poles 17 and 18 arranged to produce a magnetic field generally indicated at 19 in FIG. 2. The strength of the field may be increased in the direction of mass travel along the path 15 by bringing the poles closer together at points opposite the higher numbered electrodes, i.e. the poles may taper in the direction 15 as illustrated in FIG. 2a. It is clear from FIGS. 1 and 2 that the magnetic field extends generally perpendicular to the direction 15 of mass travel or flow, the symbol 20 in FIG. 1 showing the direction of the field as extending into the field and into the pole 17.

As the burst of ionized plasma passes the electrodes it interacts with the magnetic field 19 to produce a voltage difference between the electrodes of each pair. When a load is connected across the electrodes, current will flow and part of the kinetic energy of the plasma will be converted to electrical energy and dissipated in. the load, the plasma experiencing a loss in velocity as a result of this interaction. The electrical output from each electrode pair will be in the form of a pulse having an approximately rectangular shape, the pulses at successive electrode pairs occurring serially in time, with or without overlap, depending, among other things, on electrode width and spacing.

An important aspect of the invention concerns the provision of what may be characterized as circuit means to transmit sequentially and to control sequential transmission of the generated signals in selected code pattern. One form of such circuit means as illustrated in FIG. 1 includes individually controllable switches 21-25, of double pole single throw type, for controlling signal transmission from the respective electrodes to active and passive load elements 26 and 27. Thus, the first poles of the switches are shown as connected through a common lead 28 to the passive or dummy load 27 whereas the second poles of the switches are connected through a common lead 29to a normal or active load 26, the latter typically comprising a magnetron or klystron oscillator. Thus the output of each electrode pair may be connected to either the normal load 26, or to the dummy load 27.

By selective manipulation of the switches, sequential transmission of the signals generated at the electrode pairs may be controlled in selected code pattern, whereby pulse code trains may be generated and delivered to the normal load. For example, the number of electrode pairs and switches employed will vary in application depending upon the character of the required code. Also, one code pulse train will be generated for each burst of plasma that is genera-ted and caused to flow along the channel proximate the electrode pairs.

Since power is taken from the electrode pairs only when a load is connected thereto, the plasma burst will be slowed down only when that electrode pair is connected to a load. In the multiple electrode pair device illustrated, the plasma velocity and consequently the electrical output pulse width will vary depending upon how many of the upstream electrode pairs were loaded. This problem may be avoided by always loading each electrode pair with either the normal load 26 or a dummy load 27 of equal magnitude, the switches being manipulated to achieve this purpose. Thus, if it is desired to transmit a pulse code train characterized by closing the switches 21, 22 and 25 to normal load, the switches 23 and 24 will be closed to the dummy load 27.

Another problem arises as a result of the output voltage being a function of plasma velocity. Since the plasma velocity will decrease as the burst proceeds down the channel the output voltage will be lower at the downstream electrodes. This problem is avoided by providing the magnetic field to have strength which increases along the channel as previously described. Thus, in FIG. 2a the spacing of the magnetic pole faces 17a and 18a becomes narrower at the downstream end of the channel where for example a ferromagnetic core or pole piece is used. If a ferromagnetic core is not used, the winding geometry thereof may be adjusted to accomplish the same end. Another way of solving this problem with a ferromagnetic core involves the use of an auxiliary winding n the core and connected across a voltage source characterized as providing an exciting current increasing with time to provide a higher field strength at the time required.

FIG. 1 shows such an auxiliary winding split in two parts 30 and 31, the former being placed across the normal load and the latter across the dummy load 27, thus providing a voltage source which is synchronized with the plasma burst. In particular, as the plasma burst slows the magnetic field strength will increase in order to keep the output voltage constant, the circuit being characterized as of positive feedback type. The principal winding on the core is shown at 32 as being supplied from a current source 33. The resistors R1 and R2 in series with the respective windings 30 and 31 are required to keep output impedance positive. They can be included in the winding resistance and if the compensation windings 30 and 31 are small, loop gain may be low enough that R1 and R2 may be omitted.

The previously referred to decreasing longitudinal gap between successive electrode pairs compensates for the slowing down of plasma velocity, in such a way to result in approximately equal time increments between pulses produced at the successive electrode pairs. Of course, should it be desired to provide differential time increments, the gaps between the electrode pairs may be suitably variably adjusted, this adjustment facilitating another dimension to coding through predetermined changing of the pulse intervals.

FIG. 3 shows the application of the invention wherein the mass ejector comprises a device for shooting an ionized plasma, or an electrically conductive pellet such as a bullet 35, the ejecting device typically comprising a gun or pistol 36. The electrode pairs 14 are connected through appropriate switches, not shown in FIG. 3, with a magnetron type load generally indicated at 37, the output of which is conducted at 38 to antenna 39 for directionally beaming the resultant signal containing the pulse code train information. Such a device is clearly useful as a simple small size code signal generator and transmitter, adapted to be carried by military personnel. FIG. 4 shows an electrically conductive pellet or bullet 35 traveling in the direction of arrows 41 and contacting the brushes 42 on the electrodes 10-14, whereby the electrodes of each pair have electrically conductive interaction with the passing pellet. The direction of the magnetic field is shown at 142. Accordingly, a signal is produced as the pellet passes each electrode pair, and the coding circuit similar to FIG. 1 may be utilized to provide selective control of signal transmission to a load.

Finally, FIG. 5 shows the signal producing instrumentalities as comprising coils 43 and 44 (and more if desired) wound on the poles 45 and 46 of the C-shaped permanent magnet 47, so that portions of the coils extend in the gap 48 as illustrated. When a ferromagnetic pellet 49 having high permeability is ejected to travel in the direction of arrow 50, the flux or magnetic field in the gap is distorted by the pellet. Accordingly, the distortion and spring back of the field across the successive coils 43 and 44 produces time spaced electrical pulses in the coil leads 51 and 52, which may be connected to the load 53 by coding switches 54 and 55.

I claim:

1. Apparatus of the character described, comprising a series of electrical signal producing instrumentalities, means for energizing said instrumentalities including a mass injector to direct ejected mass along a path passing said instrumentalities in sequence, said means also including equipment to produce a magnetic field extending in such proximity to said instrumentalities and said path as to interact with said mass to induce signal current production in said instrumentalities in desired time sequence, and circuit means to transmit sequentially and to control sequential transmission of said signals in selected code pattern.

2. The invention as defined in claim 1 in which said equipment has magnetic poles arranged to produce a magnetic field the strength of which increases in the direction of mass movement along said path.

3. The invention as defined in claim 1 including load means for receiving said signals, and means cooperating with said load means to increase the strength of said field as said mass travels along said path to effect signal pro duction.

4. The invention as defined in claim 1 in which said circuit means includes individually controllable switches for controlling signal transmission from said instrumentalities.

5. The invention as defined in claim 4 including load means with respect to which the switches are connected in parallel.

6. The invention as defined in claim 5 in which said load means comprise normal load and dummy load elements, the switches are of double pole type, the first poles connected to the dummy load element and the second poles connected to the normal load element.

7. The invention as defined in claim 1 in which said instrumentalities comprise series longitudinally spaced electrode pairs, the electrodes of each pair being laterally spaced at opposite sides of said path.

8. The invention as defined in claim 7 in which the gaps between successive pairs of electrodes decrease in longitudinal dimension in the direction of said path.

9. The invention as defined in claim 1 in which said first means includes a ferromagnetic pellet to be ejected by said ejector.

10. The invention as defined in claim 9 in which said instrumentalities comprise coils, and said first means includes magnetic poles on which said coils are wound, said poles producing magnetic flux to be distorted by said pellet.

11. The invention as defined in claim 1 in which said first means include an electrically conductive pellet to be ejected by said ejector, and said instrumentalities comprise series longitudinally spaced electrode pairs, the electrodes of each pair being laterally spaced at opposite sides of said path to have electrically conducting interaction with the passing pellet.

12. The invention as defined in claim 1 including high frequency electromagnetic'signal transmitting apparatus connected to said circuit means to transmit a high frequency signal modulated in accordance with said selected code pattern signals.

13. The apparatus of claim 1 in which said mass ejector comprises a source of electrically conductive plasma.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS 6 FOREIGN PATENTS 362,032 10/22 Germany.

g -5 1x 53; NEIL c. READ, Primary Examiner.

4/62 Wolfe et a1. 328-44 ROBERT H. ROSE, Examiner.

9/62 Lemelson 340-348 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,206, 742 September 14 1965 Thomas P. Prouty ppears in the above numbered pat- It is hereby certified that error a aid Letters Patent should read as ent requiring correction and that the s corrected below.

Column 4, line 15, for "injector" read ejector Signed and sealed this 12th day of April 1966 (SEAL) Attest:

ERNEST W. SWIDER Attesting Officer Commissioner of Patents EDWARD J. BRENNER- 

1. APPARATUS OF THE CHARACTER DESCRIBED, COMPRISING A SERIES OF ELECTRICAL SIGNAL PRODUCING INSTRUMENTALITIES, MEANS FOR ENERGIZING SAID INSTRUMENTALITIES INCLUDING A MASS INJECTOR TO DIRECT EJECTED MASS ALONG A PATH PASSING SAID INSTRUMENTALITIES IN SEQUENCE, SAID MEANS ALSO INCLUDING EQUIPMENT TO PRODUCE A MAGNETIC FIELD EXTENDING IN SUCH PROXIMITY TO SAID INSTRUMENTALITIES AND SAID PATH AS TO INTERACT WITH SAID MASS TO INDUCE SIGNAL CURRENT PRODUCTION IN SAID INSTURMENTALIEIS IN DESIRED TIME SEQUENCE, AND CIRCUIT MEANS TO TRANSMIT SEQUENTIALLY AND TO CONTROL SEQUENTIAL TRANSMISSION OF SAID SIGNALS IN SELECTED CODE PATTERN. 